How do die casting defects occur?
June
www.xy-global.com
2022-02-16 18:42:18
1. The geometry and size of castings do not match the drawings
The reasons for the inconsistency between the geometry and shape of the castings and the drawings are as follows:
1. The forming part of the mold has been damaged, but the production has not been found and continues to produce.
2. The metal objects on the parting surface of the mold are not cleaned, resulting in changes in the dimensions related to the parting surface.
3. There is residue in the cavity.
2. The chemical composition of the alloy is not up to standard
The main reason is:
1. The smelting process is not carried out in accordance with the technical specifications.
2. Elements with low holding time and low melting point are easy to burn and change in composition.
3. The management of the return material is poor, the alloys of different grades are mixed, and the grade of the return material is not strictly distinguished.
4. Improper ratio of returned material and new material.
3. The geometry and size of castings do not match the drawings
The reasons for the inconsistency between the geometry and shape of the castings and the drawings are as follows:
1. The mold forming is all damaged, but the production is not pioneered and continues to be produced.
2. The movable forming part of the mold (such as the slider) can no longer be kept in the proper position (such as insufficient wedge tightening, changing the fixing position).
3. The metal objects on the parting surface of the mold are not cleaned, resulting in an innovation of the dimensions related to the parting surface.
4. There is residue in the cavity.
Fourth, the chemical identity of the alloy is consistent with the standard
The main reasons are:
1. The smelting process is not terminated according to the process regulations.
2. Elements with thermal insulation and low melting point are prone to burning and damage, and their properties are reformed.
3. The return material is poorly designed, the alloys of different brands are mixed, and the grade of the return material is not properly identified.
5. The ratio of returned material and new material is inappropriate.
6. The raw materials are not analyzed and judged when they enter the factory.
1. How many states and dimensions of the castings do not match the drawings
The reasons why the number of castings and the state of the castings do not match the drawings are as follows:
1. The mold forming part has been relaxed, but the production does not create inventions and continues to produce.
2. The movable forming part of the mold (such as the slider) can no longer be kept in its proper position (such as insufficient wedge tightening, changing the fixing position).
3. The metal objects on the parting surface of the mold are not cleaned, and even the dimensions related to the parting surface are changed.
4. There is residue in the cavity.
2. The difference scale of chemical composition of alloys
The main reasons are:
1. The smelting process is not stopped according to the process regulations.
2. Elements with low melting point and heat preservation time are easily burned, and the composition changes.
3. The design of the return material is not good, the alloys of different grades are turbid, and the grade of the return material is not well distinguished.
4. The ratio of returned material and new material is not correct.
7. No analysis was made when the raw materials entered the factory.
8. When preparing alloys, the calculation of ingredients is not rough, the addition of ingredients is wrong, and the weighing is inaccurate.
Nine, the difference scale of the hysteresis properties of the alloy
The main reasons are:
1. In the chemical composition of the alloy, the content of the elements that have the primary influence on the hysteresis performance is wrong, and the impurity content is extremely high.
2. If the heat preservation time is too long or the overheating temperature is too high, the grain size of the alloy is small.
3. Melting is not rough.
4. The ratio of the returned material to the new material is not correct, the amount of returned material is appropriate or the returned material is not graded.
5. The alloy ingots are piled up in the open air outdoors, and the oxides are appropriate.
6. The test rod casting process is different.
Ten, mesh marks, mesh burrs
The thermal cracking of the whole mold constitutes the traces and general metal thorns in the casting, and because of the thermal cracking of the mold, a mesh (spray shape) appears. When the degree of thermal cracking is relatively light, the traces printed on the casting are mesh marks ; And when the degree of thermal cracking is critical, cracks are often formed, and there are mesh burrs on the casting. The higher the melting point of the alloy, the more critical the situation of this hot cracking composition. For example, the mold of copper alloy is more vulnerable to thermal cracking. And color metal die-casting is more and more critical.
The mesh marks on the die casting machine are generally not limited. When the mesh burr is at a small level, individual is allowed; when it reaches a dangerous level, it depends on the conditions of use.
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